Immigration Increases Risk of Depression

Action Points

Note that in this study, migrants to the U.S. from Mexico had a higher risk for depressive or anxiety disorders than the nonmigrants who stayed at home in Mexico.

Note also that the elevated risk was seen primarily in younger age groups.

Note that a potential limitation of the study is the possibility of residual confounding by pre-migration differences between migrants and nonmigrants within families.

Migrating from Mexico to the U.S. may be harmful to your mental health.

That's the implication of a new study that shows that migrants are more likely to have depression or anxiety than are relatives of migrants who stayed in Mexico, according to Joshua Breslau, PhD, ScD, of the University of California Davis, in Sacramento, and colleagues.

The increased risk of depression or anxiety is mostly driven by younger migrants, Breslau and colleagues reported in the April issue of Archives of General Psychiatry.

About 12 million people living in the U.S. in 2007 were born in Mexico, the researchers noted, making up 25% of the U.S. Hispanic population and 10% of the total Mexican-born population on both sides of the border.

Some researchers have suggested that adverse experiences that are part of immigration may affect a migrant's mental health, Breslau and colleagues noted -- a hypothesis supported by observations in studies conducted in the U.S.

But only one analysis -- a small pilot study reported in 2007 by Breslau and colleagues -- has looked at differences in mental health status among migrants and those who remained in Mexico.

To fill the gap, the researchers conducted a larger study, interviewing 554 migrants to the U.S. and 2,519 Mexican residents with a family member who had migrated.

The Mexican residents formed a comparison group intended to minimize differences on the family level -- such as income or social status -- that might contribute to migration, the researchers reported.

The participants were interviewed face-to-face by investigators using the mental health version of the World Health Organization's Composite International Diagnostic Interview in both countries.

The main outcome measure was first onset of any depressive or anxiety disorder, Breslau and colleagues reported. Depressive disorders included major depression and dysthymia, while anxiety disorders included social phobia, panic disorder, post-traumatic stress disorder, and generalized anxiety disorder.

They found:

Migrants had a significantly higher risk for depressive or anxiety disorders than did nonmigrants; the odds ratio was 1.42, with a 95% confidence interval from 1.04 to 1.94.

The risk of depressive disorders did not reach significance when considered alone, but the risk of anxiety disorders did, with an odds ratio of 1.78 and a 95% confidence interval from 1.12 to 2.83.

Among the four anxiety disorders, generalized anxiety disorder and social phobia reached significance, with odds ratios of 2.39 and 2.16, respectively.

The association between migration and disorder varied across birth cohorts, with the elevated risk restricted to those ages 18 through 25 or 26 through 35 years when interviewed. The odds ratios for any depressive or anxiety disorder for those groups were 3.89 and 1.83, respectively.

When depressive and anxiety disorders were considered as separate groups according to birth cohort, the risk was only significantly increased in the youngest cohort, with odds ratios of 4.37 and 3.40, respectively.

The finding is "the first direct evidence that experiences as a migrant might lead to the onset of clinically significant mental health problems in this population," Breslau and colleagues argued.

Although the researchers chose the comparison group to minimize the effect of family level differences among migrants and nonmigrants, they cautioned that residual confounding on an individual level remains possible.

They added that recall bias may affect estimates of lifetime prevalence of the disorders, although since the increased risk was mainly among younger participants, that should be minimized.

The study was supported by the National Institute of Mental Health, the National Institutes of Health, and the University of California Migration and Health Research Center.

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